One vertex per element, one color per generator, with an edge from x to x·s.
(5,8)(9,10)(11,18)(12,16)(13,22)(14,17)(15,20)(19,23)(21,24)(25,26,30,34)(27,35,37,40)(28,33,29,32)(31,38,39,36)(1,2,4,6)(3,5,7,8)(9,11,14,21)(10,15,17,23)(12,20,13,19)(16,24,22,18)(1,3,4,7)(2,5,6,8)(25,27)(26,31)(28,36)(29,38)(30,37)(32,35)(33,40)(34,39)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,18,23,24)(25,28,30,29)(26,32,34,33)(27,36,37,38)(31,35,39,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.